The family of herpes viruses is responsible for a wide range of infections that afflict humans and many important domestic animals. The diseases caused by these viruses range from bothersome cold sores to highly destructive infections of the central nervous system (encephalitis). The more common members of this family include herpes simplex virus (types 1 and 2) responsible for cold sores and genital lesions; varicella zoster virus which causes chicken pox and shingles; and Epstein-Barr virus which causes infectious mononucleosis. Although some significant advances have been made in the last decade in antiviral therapy, the need for effective, safe therapeutic agent for treating herpes viral infections continues to exist. For a recent review of current therapeutic agents in this area, see M. C. Nahata, "Antiviral Drugs: Pharmacokinetics, Adverse Effects and Therapeutic Use", J. Pharm. Technol., 3, 100 (1987).
The present application discloses a group of cyclic peptide derivatives having activity against herpes viruses. The relatively selective action of these peptides against herpes viruses, combined with a wide margin of safety, renders the peptides as desirable agents for combating herpes infections.
The association of peptides with anti-herpes activity is uncommon. Instances of reports of such an association include B. M. Dutia et al., Nature, 321, 439 (1986), E. A. Cohen et al., Nature, 321, 441 (1986), J. H. Subak-Sharpe et al., UK patent application 2185024, published Jul. 8, 1987, E. A. Cohen et al., European patent application 246630, published Nov. 25, 1987, R. Freidinger et al., European patent application 292255, published Nov. 23, 1988, and R. Freidinger et al., U.S. Pat. No. 4,814,432, issued Mar. 21, 1989. The subject peptides of the previous reports can be distinguished from the peptides of the present application by characteristic structural and biological differences.